High frequency power amplifying apparatus having amplifying stages with gain control signals of lower amplitudes applied to earlier preceding stages

ABSTRACT

A high frequency power amplifying apparatus is provided with an amplifying section with a plurality of amplifying stages connected in cascade. A power control signal is supplied to the amplifying section through a control terminal so as to control the output of the high frequency power amplifying apparatus. Each of the amplifying stages has a gain smaller than that of a preceding stage. Gain control signals generated from the power control signal are supplied to the respective amplifying stages. Dividing resistors are connected in series with one another between the control terminal and a reference potential so as to divide the voltage of the power control signal to thereby generate a plurality of different gain control signals. Different ones of the gain control signals are supplied to the respective amplifying stages, an absolute value of a voltage of the gain control signal applied to each stage is smaller than that applied to an earlier preceding stage.

This is a continuation application of U.S. Ser. No. 09/550,903, filedApr. 17, 2000.

BACKGROUND OF THE INVENTION

The present invention relates to a high frequency power amplifyingapparatus for a multi-band communication system or a multi-modecommunication system, and a radio communication apparatus in which thehigh frequency power amplifying apparatus is incorporated. Particularlythe invention relates to a technique which is effective in applicationsto a high frequency power amplifying apparatus (high frequency poweramplifying module: PA module) with a plurality of amplifying sections,such as one for a dual-band communication system, and a radiocommunication apparatus, such as a mobile communication apparatus, inwhich the high frequency power amplifying apparatus is incorporated.

A high frequency power amplifier is used in a transmitter portion of amobile communication apparatus such as a mobile telephone, a portabletelephone, or the like.

A dual-band communication system is known as a system which canestablish communication between portable telephones (for example,cellular telephones) which are different in communication system. Such adual-band system is described, for example, in “THE HITACHI HYORON” byHitachi Hyoron-sha, Vol. 80, No. 11 (1998), pp. 47-52. In the samedocument, there is description about a dual-band system and a dual-bandhigh frequency power amplifier (RF module: PA module) which are based onGSM (Global System for Mobile Communications) having a carrier frequencyband in a range of from 880 MHz to 915 MHz and DCS-1800 (DigitalCellular System 1800) having a carrier frequency band in a range of from1,710 MHz to 1,785 MHz. The document also discloses a triple-mode systemas a composite apparatus.

On the other hand, JP-A-11-186921 (published on Jul. 9, 1999) disclosesa multi-band mobile communication apparatus which is available forportable telephone systems such as PCN (Personal Communications Network:DCS-1800), PCS (Personal Communications Service: DCS-1900), GSM, and soon.

A dual-band high frequency power amplifying module is configured to havetwo amplifying sections (high frequency power amplifying sections) eachconstituted by two or more transistors (amplifiers) connected in cascadesequentially.

In the background art, in order to apply control voltages to transistorsin respective stages independently of one another, a general highfrequency power amplifying apparatus (RF power amplifier module) dividesthe voltage of a power control signal Vapc by resistors to therebysupply desired gate biases to the transistors.

Such a configuration has an advantage that gate biases to thetransistors in the respective stages can be established independently ofone another. However, an electric current also flows into the gates ofthe respective transistors. Accordingly, when such a configuration isapplied to a dual or more RF power amplifier having two amplifyingsections, a power control current Iapc becomes unable to satisfy thecurrent consumption specification.

If the resistance of a control voltage supply circuit is to be increasedto solve the above-mentioned problem, the CR time constant defined bythe resistance and the gate-to-drain parasitic capacitance of a MOStransistor is increased. As a result, a request to the transistor forthe switching rate cannot be performed satisfactorily.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a high frequencypower amplifying apparatus with a plurality of amplifying sections inwhich biases of transistors in the respective amplifying sections can beset to be proper enough to attain high linearity.

It is another object of the present invention to provide a highfrequency power amplifying apparatus with a plurality of amplifyingsections, which is superior in switching characteristic.

It is a further object of the present invention to provide a highfrequency power amplifying apparatus with a plurality of amplifyingsections, in which only one switching terminal is provide and which isconvenient to use.

It is a still further object of the present invention to provide a highfrequency power amplifying apparatus with a plurality of amplifyingsections, which can achieve reduction of the power consumption.

It is another object of the present invention to provide a radiocommunication apparatus for a multi-band communication system or amulti-mode communication system, which is superior in performance andwhich can reduce the power consumption.

In a high frequency power amplifying apparatus with amplifying sectionseach having a plurality of amplifying stages connected in cascade, apower control signal is supplied to the amplifying sections through acontrol terminal so as to control the output of the high frequency poweramplifying apparatus. According to an aspect of the present invention,in the light of the fact that the respective amplifying stages in theamplifying sections are usually formed in the same manufacturing processwith a result that earlier preceding amplifying stages have larger gain,dividing resistors are connected in series with each other between thecontrol terminal and a reference potential to divide the voltage of thepower control signal so as to generate a plurality of different gaincontrol signals. Each amplifying stage is supplied with one of the gaincontrol signals thus generated. The voltage of the gain control signalsupplied to an amplifying stage has a smaller absolute value than thatof the gain control signal supplied to an earlier preceding stage.

According to another aspect of the present invention, there is provideda high frequency power amplifying apparatus comprising:

a plurality of amplifying stages including at least first and finalstages, each of the plurality of amplifying stages having a firstterminal for receiving an input signal to the stage, a second terminalfor sending out an output signal of the stage, and a third terminal forreceiving a reference potential for the stage, the first terminal of thefirst stage being adapted to receive a high frequency input signal tothe high frequency power amplifying apparatus, the second terminal ofthe final stage being adapted to send out a high frequency output signalof the high frequency power amplifying apparatus, the second terminal ofeach amplifying stage except the final stage being electricallyconnected to the first terminal of a stage succeeding thereto, each ofthe amplifying stages except said first stage having a gain smaller thanthat of a stage preceding thereto;

a control terminal for receiving a power control signal; and

a plurality of dividing resistors connected in series with one anotherbetween the control terminal and a reference potential for dividing avoltage of the power control signal to thereby generate a plurality ofdifferent gain control signals, different ones of the plurality of gaincontrol signals being supplied to different ones of the first terminalsof the plurality of amplifying stages respectively, an absolute value ofa voltage of the gain control signal applied to the first terminal ofeach stage being smaller than that of the gain control signal applied tothe first terminal of an earlier preceding stage.

According to another aspect of the present invention, there is provideda high frequency power amplifying apparatus comprising:

a first amplifying section having a plurality of amplifying stages eachincluding at least first and final stages, each of the plurality ofamplifying stages having a first terminal for receiving an input signalto the stage and a bias signal for the stage, a second terminal forsending out an output signal of the stage and a third terminal forreceiving a reference potential for the stage, the first terminal of thefirst stage being adapted to receive a first high frequency input signalto the high frequency power amplifying apparatus, the second terminal ofthe final stage being adapted to send out a first high frequency outputsignal of the high frequency power amplifying apparatus, the secondterminal of each amplifying stage except the final stage beingelectrically connected to the first terminal of a stage succeedingthereto, each of the amplifying stages except the first stage having again smaller than that of a stage preceding thereto;

a second amplifying section having a plurality of amplifying stages eachincluding at least first and final stages, each of the plurality ofamplifying stages having a first terminal for receiving an input signalto the stage and a bias signal for the stage, a second terminal forsending out an output signal of the stage and a third terminal forreceiving a reference potential for the stage, the first terminal of thefirst stage being adapted to receive a second high frequency inputsignal to the high frequency power amplifying apparatus, the secondterminal of the final stage being adapted to send out a second highfrequency output signal of the high frequency power amplifyingapparatus, the second terminal of each amplifying stage except the finalstage being electrically connected to the first terminal of a stagesucceeding thereto, each of the amplifying stages except the first stagehaving a gain smaller than that of a stage preceding thereto;

a control terminal for receiving a power control signal;

a first series of dividing resistors connected in series with oneanother between the control terminal and a reference potential fordividing a voltage of the power control signal to thereby generate aplurality of different first gain control signals, different ones of theplurality of first gain control signals being supplied as the biassignals to the respective first terminals of the plurality of amplifyingstages in the first amplifying section, an absolute value of a voltageof the first gain control signal applied to the first terminal of eachstage being smaller than that of the first gain control signal appliedto the first terminal of an earlier preceding stage;

a second series of dividing resistors connected in series with oneanother between the control terminal and the reference potential fordividing a voltage of the power control signal to thereby generate aplurality of different second gain control signals, different ones ofthe plurality of second gain control signals being supplied as the biassignal to the respective first terminals of the plurality of amplifyingstages in the second amplifying section, an absolute value of a voltageof the second gain control signal applied to the first terminal of eachstage being smaller than that of the second gain control signal appliedto the first terminal of an earlier preceding stage;

a selection circuit connected to the first and second series ofseries-connected resistors, said selection circuit being responsive toan amplifying-section selection signal to cause the power control signalto be supplied to one of the first series of series-connected resistorsand the second series of series-connected resistors and cause the powercontrol signal to be blocked from being supplied to the other of thefirst and second series of series-connected resistors in order to makeone of the first and second amplifying sections active and make theother inactive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram showing a dual-band highfrequency power amplifying apparatus devised by the present inventorsand examined previously to the present invention;

FIG. 2 is an equivalent circuit diagram of a dual-band high frequencypower amplifying apparatus according to an embodiment (Embodiment 1) ofthe present invention;

FIG. 3 is a perspective view showing the external appearance of thedual-band high frequency power amplifying apparatus of Embodiment 1;

FIG. 4 is a bottom view of the dual-band high frequency power amplifyingapparatus of Embodiment 1;

FIG. 5 is a plan view schematically showing the layout of electronicparts on a connection board in the dual-band high frequency poweramplifying apparatus of Embodiment 1;

FIG. 6 is a graph showing a correlation between switching time of anamplifying section and an output thereof;

FIG. 7 is a block diagram showing the system configuration of a mobilecommunication apparatus in which the high frequency power amplifyingapparatus of Embodiment 1 is incorporated;

FIG. 8 is an equivalent circuit diagram of a dual-band high frequencypower amplifying apparatus according to another embodiment (Embodiment2) of the present invention;

FIG. 9 is a circuit diagram showing the circuit configuration inEmbodiment 1 in more detail;

FIG. 10 is a graph useful in explaining the operation of the highfrequency power amplifying apparatus shown in FIG. 9; and

FIG. 11 is a graph showing the output characteristic of the, highfrequency power amplifying apparatus shown in FIG. 9.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

For a better understanding of the present invention, first, descriptionwill be made about a high frequency power amplifying apparatus which hasbeen devised and examined by the inventors of the present application.Therefore, the structure shown in FIG. 1 does not belong to knowntechnology as long as the inventors of the present application know.

FIG. 1 is an equivalent circuit view showing a dual-band high frequencypower amplifying apparatus examined previous to the present invention,which is arranged so that MOSFETs (Metal Oxide SemiconductorField-Effect-Transistors) are incorporated in three stages (initialstage (first stage), second stage, and final stage (third stage)) ineach amplifying section.

As shown in FIG. 1, the two amplifying sections are constituted by anamplifying section a in which a first-stage transistor circuit Q1′, asecond-change transistor circuit Q2′ and a final-stage transistorcircuit Q3′ are connected in cascade between an input terminal Pin1 andan output terminal Pout1, and an amplifying section b in which afirst-stage transistor circuit Q4′, a second-stage transistor circuitQ5′ and a final-stage transistor circuit Q6′ are connected in cascadebetween an input terminal Pin2 and an output terminal Pout2.

In the amplifying section a, the gate terminals of the respectivetransistor circuits Q1′, Q2′ and Q3′ are connected not only to the drainterminal of a switching transistor Q7′ through voltage dividingresistors R22 to R27 respectively but also to a control terminal Tapc towhich a control voltage Vapc is supplied through a load resistor R28. Inaddition, the gate terminal of the switching transistor Q7′ is connectedto a switching terminal Tc1 to which a switching voltage Vct1 issupplied through a gate-impedance matching resistor R21 while the sourceterminal of the switching transistor Q7′ is connected to the ground(GND).

In the amplifying section b, the gate terminals of the respectivetransistor circuits Q4′, Q5′ and Q6′ are connected not only to the drainterminal of a switching transistor Q8 through voltage dividing resistorsR32 to R37 respectively but also to the control terminal Tapc of thepower amplifying apparatus through a load resistor R38. In addition, thegate terminal of the switching transistor Q8′ is connected to aswitching terminal Tc2 to which a switching voltage {overscore (Vct1)}is supplied through a gate-impedance matching resistor R31 while thesource terminal of the switching transistor Q8′ is connected to GND.

Further, the drain terminals of the transistor circuits Q1′ to Q6′ areconnected to a power supply terminal Vdd.

To give examples to the resistance values of the resistors, theresistors R28 and R38 take values of 1.8 kΩ; R22, R24, R26, R32, R34 andR36, 2.3 kΩ; and R23, R25, R27, R33, R35 and R37, 300Ω.

In such a high frequency power amplifying apparatus, the switchingtransistors Q7′ and Q8′ are actuated alternately on the basis of signalsVct1 and {overscore (Vct1)} applied to the switching terminals Tc1 andTc2 so as to use the amplifying section a or b selectively so that poweramplification is performed on high frequency signals in different bands.

That is, when the amplifying section a from the input terminal Pin1 tothe output terminal Pout1 is actuated, the switching terminals Tc1 andTc2 are set to be “Low” and “High” respectively. As a result of thissetting, a current flows into the respective resistors R21 to R28 in theamplifying section a while a current also flows into the resistor R38 inthe amplifying section b.

At this time, the switching transistor Q8′ in the amplifying section boperates so that the potential at a node A on the drain side of theswitching transistor Q8′ becomes close to 0V.

When the amplifying section b operates, on the other hand, a currentflows into the respective resistors R31 to R38 in the amplifying sectionb while a current also flows into the R28 in the amplifying section a inthe same manner as in the foregoing case. Then, the potential at a nodeB on the drain side of the switching transistor Q7′ becomes close to 0V.

In order to restrain the current consumption, it is therefore necessaryto set the resistors R28 and R38 to be a high resistance value, forexample, not less than 2 kΩ.

However, if the resistance value of the resistor R28 is set to be high,the potential at the node B will be low when the amplifying section e isoperating. Thus, respective biases cannot be set to take their propervalues (for example, bias values required for making the respectiveamplifying stages active).

If the resistance values of the voltage dividing resistors R22, R24 andR26 are set to be high enough to set the respective biases to take theirproper values, a request to the respective stages for the switching ratecannot be then satisfied.

Further, in the circuit arrangement shown in FIG. 1, two switchingterminals Tc1 and Tc2 are required. It is troublesome to handle them.

Embodiments of the present invention will be described below in detailwith reference to the drawings. Incidentally, in all the drawings forexplaining the embodiments of the present invention, the same orcorresponding parts are referenced correspondingly, and theirdescription will not be repeated.

Embodiment 1

In Embodiment 1, description will be made about an example in which thepresent invention is applied to a mobile communication apparatus for adual-band communication system having two amplifying sections, and ahigh frequency power amplifying apparatus to be incorporated in themobile communication apparatus.

FIGS. 2 to 5 are diagrams relating to a dual-band high frequency poweramplifying apparatus (RF power amplifier module: or PA module) accordingto an embodiment (Embodiment 1) of the present invention.

A dual-band PA module 1 according to Embodiment 1 has a flat rectangularparallelepiped structure as shown in the perspective view of FIG. 3.That is, the dual-band PA module 1 includes a flat rectangularparallelepiped package 4 having a plate-like connection board 2 and acap 3 provided on this connection board 2 so as to cover one surface(main surface) of the connection board 2.

More specifically, the dual-band PA module 1 has a configuration inwhich, for example, active parts such as transistors, etc. and passiveparts such as chip resistors, chip capacitors, etc. are mounted on theone surface of the connection board 2 having a multi-layer structure,and a plurality of transistors are connected in cascade so as to formtwo multi-stage amplifying sections.

In Embodiment 1, the high frequency power amplifying apparatus includesfirst and second amplifying sections. In addition, each of the highfrequency power amplifying sections has a three-stage structure (initialstage (first stage), second stage, final stage (third stage)) in whichthree transistors are connected in cascade. Insulated-gate field-effecttransistors, for example, MOSFETs are used as the respectivetransistors, not by way of limitation.

In addition, the one surface of the connection board 2 is covered withthe cap 3 which is made of metal and which plays a role ofelectromagnetic shielding effect. The cap 3 is electrically connected toa GND terminal of the connection board 2.

External electrode terminals (electrode terminals) which areelectrically independent of the foregoing package 4 project therefrom.That is, in this embodiment, surface-mounting external electrodeterminals are provided at the circumferential edge of the lower surface(bottom surface) of the connection board 2 as shown in FIG. 4 whichshows the bottom surface of the PA module 1 of FIG. 3.

As the foregoing external electrode terminals, a first-amplifyingsection input terminal (Pin1); a switching terminal Tct for selectivelyswitching between the first amplifying section and the second amplifyingsection; a reference potential terminal (for example, ground terminal:GND); a power supply potential terminal (for example, power supplyterminal: Vdd); and a first-amplifying section output terminal Pout1 areprovided along one edge of the package 4 in the order from the left tothe right as shown in FIG. 4. Along the opposite edge of the package 4,a second-amplifying section input terminal (Pin2); a control terminal(Tapc); GND; and a second-amplifying section output terminal (Pout2) areprovided in the order from the left to the right. These externalelectrode terminals are provided over the connection board 2 to extendfrom its side surfaces to its bottom surface.

Further, the dual-band PA module 1 according to Embodiment 1 has asurface-mounting structure using soldering or the like. In thisstructure, as shown in FIG. 4, GND conductor is covered with a resistfilm 5 which is optionally provided so that solders for respectiveconnection areas are made even in thickness on the bottom surface of theconnection board 2. Thus, the reliability can be ensured when thedual-band PA module 1 is installed.

FIG. 1 is an equivalent circuit diagram of the dual-band PA module 1according to Embodiment 1. In Embodiment 1, each of high frequency poweramplifying sections e and f of the high frequency power amplifyingapparatus has three amplifying stages connected in cascade.

In the first amplifying section e, a first-stage transistor circuit(first amplifying stage) Q1, a second-stage transistor circuit (secondamplifying stage) Q2 and a final-stage transistor circuit (finalamplifying stage) Q3 are connected in cascade sequentially. Eachamplifying stage has a first terminal for receiving an input signalsupplied to the stage, a second terminal for sending out an output ofthe stage, and a third terminal for receiving a reference potential forthe stage. The first terminal in the first stage acts as a first inputterminal Pin1 for receiving a first input signal to the high frequencypower amplifying apparatus. The second terminal in the final stage actsas a first output terminal Pout1 for sending out an output signalamplified by the high frequency power amplifying apparatus. A switchingtransistor Q7 is provided for controlling the operation of the firstamplifying section e.

In the second amplifying section f, a first-stage transistor circuit(first amplifying stage) Q4, a second-stage transistor circuit (secondamplifying stage) Q5 and a final-stage transistor circuit (finalamplifying stage) Q6 are connected in cascade sequentially. Eachamplifying stage has first to third terminals in the same manner as inthe first amplifying section e. Thus, the first terminal in the firststage acts as a second input terminal Pin2 for receiving a second inputsignal supplied to the high frequency power amplifying apparatus. Thesecond terminal in the final stage acts as a second output terminalPout2 for sending out a second output signal amplified by the highfrequency power amplifying apparatus. A switching transistor Q8 isprovided for controlling the operation of the second amplifying sectionf.

One of the first and second amplifying sections e and f is selectivelymade active on the basis of an amplifying section selection signal Vct1applied to the switching terminal Tct1, and the other amplifying sectionis made inactive. An inverter 10 is provided among the switchingtransistors Q7 and Q8 and the switching terminal Tct1.

The inverter 10 has a transistor Q9 of an MOSFET. The control electrodeof the transistor Q9 is connected to the switching terminal Tct1 througha gate bias resistor R7. The control electrode of the switchingtransistor Q7 of the first amplifying section e is connected to thecontrol electrode of the transistor Q9 so that the gate bias to theswitching transistor Q7 is determined also by the resistor R7.

The output electrode of the transistor Q9 is connected to the controlelectrode of the switching transistor Q8 of the second amplifyingsection f. Further, the control electrode of the switching transistor Q8is connected to the power supply potential terminal (power supplyterminal: Vdd) through a resistor R8 so that a predetermined gate biasis applied to the transistor Q8. The transistors Q7 and Q8 and theinverter 10 constitute an amplifying section selecting circuit.

The gains of the respective transistor circuits (amplifying stages) inthe first and second amplifying sections e and f are controlled by apower control signal Vapc applied to the control terminal Vapc. Then,voltage dividing resistors are provided so that optimum gain controlvoltages are applied to the transistor circuits respectively, as will bedescribed later.

That is, the conductor is branched into two at a node D connected to thecontrol terminal Tapc. One of the branches feeds the first amplifyingsection e, and the other feeds the second amplifying section f.

For the first amplifying section e, the node D is connected to thecontrol electrode of the final-stage transistor circuit (finalamplifying stage) Q3 through a resistor R1. A node E between thefinal-stage transistor circuit Q3 and the resistor R1 is connected tothe control terminal (first terminal) of the second-change transistorcircuit (second amplifying stage) Q2 through a resistor R3. A node Fbetween the second-change transistor circuit Q2 and the resistor R3 isconnected to the control electrode of the first-stage transistor circuit(first amplifying stage) Q1 through a resistor R4. A node G between thefirst-stage transistor Q1 and the resistor R4 is connected to referencepotential (for example, ground potential GND) through a resistor R5. Asa result, the gate biases to the first-stage, second-stage and finalstage transistor circuits Q1 to Q3, that is, gain control signals Vg1 toVg3 are determined.

For the second amplifying section f, in the same manner as in the firstamplifying section e, the node D is connected to the control terminal ofthe final-stage transistor circuit Q6 through a resistor R6. A node Kbetween the final-stage transistor circuit Q6 and the resistor R6 isconnected to the control terminal of the second-stage transistor Q5through a resistor R10. A node L between the second-stage transistorcircuit Q5 and the resistor R10 is connected to the control terminal ofthe first-stage transistor Q4 through a resistor R12. A node M betweenthe first-stage transistor circuit Q4 and the resistor R12 is connectedto the reference potential (for example, GND) through a resistor R11. Asa result, the gate biases to the first-stage, second-stage and finalstage transistor circuits Q4 to Q6, that is, gain control signals Vg4 toVg6 are determined.

Further, the other electrodes of the switching transistors Q7 and Q8 andthe transistor Q9 are connected to the reference potential GNDrespectively.

To give examples to the resistance values of the voltage dividingresistors, R1=R6=1.2 kΩ, R2=R9=200Ω, R7=R8=10 kΩ, R3=R10=300Ω,R4=R12=300Ω, and R5=R11=2 kΩ. Incidentally, the power supply potential(Vdd) is, for example, 3.5V.

As shown in FIG. 5, the foregoing circuit is generally formed bymounting the respective electronic parts (the above-mentionedtransistors and resistors) on the connection board 2. In FIG. 5,conductors 11 are formed in a predetermined pattern on the main surfaceof the connection board 2. In addition, a wire connection pad 14 isformed by the conductors 11. Then, electrodes 12 of the respectivetransistors and the wire connection pad 14 are electrically connected toone another through conductors 13.

The dual-band PA module 1 arranged thus has two high frequency poweramplifying sections which are actuated by switching.

In Embodiment 1, the first amplifying section e may be used for poweramplification of high frequency input signals in GSM (carrier frequency900 MHz), and the second amplifying section f may be used for poweramplification of high frequency input signals in PCN (carrier frequency1.75 GHz).

The dual-band PA module 1 of Embodiment 1 is incorporated in a mobilecommunication apparatus as a radio communication apparatus by way ofexample. FIG. 7 is a block diagram of a radio portion of a mobilecommunication apparatus (portable telephone) in which such a dual-bandPA module 1 is incorporated.

As shown in FIG. 7, the dual-band portable telephone has a base bandportion 40 connected to a microphone or a speaker and including a baseband IC; a converter 41 connected to the base band portion 40 andincluding an along-to-digital converter and a digital-to-analogconverter; a signal processing portion 42 connected to the converter 41;an antenna 43; a switch 44 for switching the antenna 43 betweentransmitting and receiving operations; a dual-band PA module 1incorporated between the signal processing portion 42 and the switch 44;two low-noise amplifiers (LNAs) 45 and 46 incorporated as two sectionsbetween the signal processing portion 42 and the switch 44; an RF VCO(Voltage Controlled Oscillator) 47 connected to the signal processingportion 42; and a dual synthesizer 48 having an RF PLL and an IF PLLconnected to the RF VCO 47 and the signal processing portion 42respectively.

The signal processing portion 42 includes, as a transmitter section, amodulator 50 and a PLL (Phase-Locked Loop) 51 connected thereto. Themodulator 50 is connected to the converter 41, and the PLL 51 isconnected to the dual-band PA module 1.

In addition, the signal processing portion 42 includes, as a receiversection, two RF mixers 52 and 53 prepared for two frequency bands andrespectively connected to the low-noise amplifiers (LNAs) 45 and 46, anIF mixer 54 having an AGC (Auto Gain Control) connected to the RF mixers52 and 53, and a demodulator 55 connected to the IF mixer 54. Thedemodulator 55 is connected to the converter 41.

In addition, the dual synthesizer 48 is connected to the IF mixer 54,the modulator 50 and the demodulator 55 through an IF VCO 56 provided inthe signal processing portion 42. In addition, the RF VCO 47 isconnected to the PLL 51 and the RF mixers 52 and 53.

In the dual-band portable telephone having such a system arrangement,one LNA, one RF mixer, one RF VCO, and one amplifying section of the PAmodule are selected in accordance with a system (frequency) to be used,and the others are put in a sleep (unuse) mode. Switching them isdetermined in accordance with the traffic situation in each systemautomatically or optionally manually.

This switching signal Vct1 is supplied, for example, through a CPU 60.On the other hand, the power control signal Vapc is supplied, forexample, from an automatic power controller 62 having a conventionallyknown configuration. The automatic power controller 62 receives adetection signal indicative of the output of the PA module 1 from eitherone of couplers 64 a and 64 b coupled with an output conductor of the PAmodule 1, and further receives a reference signal Vref corresponding toa predetermined power output from the CPU 60. The automatic powercontroller 62 compares the detection signal from the coupler with thereference signal so that the power control signal Vapc is determined onthe basis of the result of the comparison. The power control signal Vapcdetermined thus is supplied to the control terminal Tapc of the PAmodule 1.

According to the dual-band portable telephone of Embodiment 1, dual-bandcommunication can be attained.

Embodiment 1 can obtain at least one of the following effects.

(1) The switching transistors Q7 and Q8 for actuating the respectiveamplifying sections (the first and second amplifying sections e and f)are configured to select one of the amplifying sections on the basis ofa switching signal Vct1 applied, through the switching terminal Tct1, tothe control electrode of the transistor Q9 of the inverter 10. As aresult, switching terminals are integrated into one, that is, theswitching terminal Vct1, so that it is convenient to handle switching.

(2) The respective transistor circuits Q1 to Q6 of the amplifyingsections (the first and second amplifying sections e and f) are suppliedwith suitable gate biases (gain control voltages) so that the biascontrol is well performed. As a result, not only is it possible toattain the improvement of the linearity in the amplificationcharacteristic of the amplifying sections but also it is possible tolower a control current (Iapc) and hence to reduce the powerconsumption. In other words, if resistors (for example, R1, R3, R4 andR5) are set to make the biases to the transistors in the respectivestages take their optimum values (high linearity), the paths of thecontrol current Iapc are integrated into one so that Iapc can bereduced. To say other words, the resistors (for example, R1, R3, R4 andR5) can be set to be low correspondingly to the reduction of the controlcurrent Iapc. Thus, the switching characteristic becomes satisfactory.

(3) In addition, the resistance values of the resistors provided betweenthe control terminal Tapc and the respective transistor circuits Q1 toQ6 can be reduced in accordance with the reduction of the currentconsumption so that the switching characteristic is improved.

FIG. 6 is a graph showing a correlation between output Pout of the poweramplifying apparatus and switching time of the amplifying sections inEmbodiment 1. As shown in the same graph, on the assumption that thespecification is satisfied when the switching time is 2 μS, it is provedthat the switching time takes 2 μS or less till the output Pout reaches35 dBm, satisfying the specification.

(4) The radio communication apparatus of Embodiment 1 includes a highfrequency power amplifying apparatus which is superior in switchingperformance and in linearity and which can reduce the currentconsumption. It is therefore possible to provide a multi-bandcommunication system which is superior in performance and which canreduce the power consumption.

Embodiment 2

FIG. 8 is an equivalent circuit diagram of a dual-band high frequencypower amplifying apparatus which is another embodiment (Embodiment 2) ofthe present invention.

The resistors R2 and R9 respectively provided between the switchingtransistor Q7 of the first amplifying section e and the node E andbetween the switching transistor Q8 of the second amplifying section fand the node K in Embodiment 1 are replaced by coils L1 and L2respectively in Embodiment 2.

In any coil, the higher its frequency is, the higher its impedance is.Therefore, when the coils L1 and L2 are disposed between the switchingtransistor Q7 and the node E and between the switching transistor Q8 andthe node K instead of the resistors R2 and R9 respectively, the node Eor K can be short-circuited to the drain electrode of the switchingtransistor Q7 or Q8 as its output electrode with respect to DC while thenode can obtain high impedance with respect to the high frequency.Although the specifications of these coils depend on the frequency, forexample, coils of 20 nH or more may be used.

For example, when the first amplifying section e from the first inputterminal Pin1 to the first output terminal Pout1 is used for GSM (900MHz) and the second amplifying section f from the second input terminalPin2 to the second output terminal Pout2 is used for PCN (1.75 GHz), theresistors R2 and R9 cannot take so large resistance values if they areincorporated. As a result, in the PCN operation, a high frequency signalleaks through the resistor R9 so that the efficiency deteriorates. Onthe other hand, when the coils L1 and L2 are used instead of theresistors R2 and R9 as in the case of Embodiment 2, high-frequencyleakage can be restrained so that the efficiency can be prevented fromdeteriorating.

Next, the embodiment of the present invention will be further describedwith reference to FIGS. 9 to 11. FIG. 9 shows the circuit arrangement ofFIG. 2 in more detail. The reference symbols L1 to L20 representmatching circuits. FIG. 10 is a graph showing changes of gain controlsignals Vg1, Vg2 and Vg3 applied to the respective amplifying stageswith respect to a change of the power control signal Vapc supplied tothe control terminal Tapc. FIG. 11 is a graph showing a change of poweroutput of the amplifying section (high frequency power apparatus) withrespect to a change of the power control signal Vapc.

In FIG. 9, as the amplifying stage is less preceding, the transistorgate width relative to the transistor gate length is larger. Thus, thereis a tendency that as the amplifying stage becomes later, its gain issmaller. If a substantially equal bias voltage, that is, an equal gaincontrol voltage (signal) is applied to the respective amplifying stagesin the amplifying section e or f, the leading edge of the power outputrelative to the power control signal Vapc in the amplifying section e orf becomes sharp as shown by the curve X in FIG. 11. This is inconvenientfor varying the power control signal Vapc to thereby control the poweroutput of the high frequency power apparatus accurately.

In the configurations according to the embodiments of the presentinvention shown in FIGS. 1, 8 and 9, as the amplifying stage of eachamplifying section is earlier, the bias voltage (gain control voltage)to be applied to the amplifying stage is made lower as shown in FIG. 10.As a result, the leading edge of the power output relative to the powercontrol signal Vapc becomes gentle as shown by the curve P1 in FIG. 11,so that the property for controlling the power output of the highfrequency power amplifying apparatus is improved.

Although the output characteristic of the amplifying section e is shownin FIG. 11, the characteristic of the output P2 of the amplifyingsection t is also designed so that as the amplifying stage is earlier,the bias voltage (gain control voltage) to be applied to the amplifyingstage is made lower as shown in FIG. 10. Thus, the characteristic of theoutput P2 of the amplifying section f is similar to that which is shownby the curve P1 in FIG. 11.

The invention developed by the inventors of this application has beendescribed specifically on the basis of its embodiments. However, theinvention is not limited to the aforementioned embodiments, but it goeswithout saying that it may be subject to various modifications withoutdeparting from its spirit.

Although description was made in the above-mentioned embodiments as toexamples in which the present invention was applied to a radiocommunication apparatus for a multi-band communication system and a highfrequency power amplifying apparatus incorporated in the radiocommunication apparatus, the present invention is similarly applicableto a radio communication apparatus for a multi-mode communication systemand a high frequency power amplifying apparatus incorporated in theradio communication apparatus, and then it can have similar effects. Inaddition, the present invention is similarly applicable to technologywith a plurality of amplifying sections different in band and mode, andthen it can have similar effects.

The present invention is applicable to any technology so long as itrelates to a high frequency power amplifying apparatus with a pluralityof amplifying sections.

According to the aforementioned various embodiments, the followingeffects can be expected.

(1) In a high frequency power amplifying apparatus, switchingtransistors for actuating respective amplifying sections are configuredso that the amplifying sections are selected on the basis of a signalapplied through a switching terminal to a control electrode of atransistor of a amplifying section selecting circuit. As a result, ifthe number of the amplifying sections is two, switching terminals areintegrated into one so that it is convenient to handle it.

(2) In the high frequency power amplifying apparatus, the respectivetransistors of the amplifying sections are supplied with suitable gatebiases so that not only is it possible to attain the improvement of thelinearity in the amplifying characteristic of the amplifying sectionsbut also it is possible to reduce the current consumption and hence toreduce the power consumption.

(3) In addition, resistance values of resistors provided between thecontrol terminal to which a power control signal is supplied and therespective transistors can be reduced in accordance with the reductionof the current consumption so that the switching characteristic isimproved.

(4) In a radio communication apparatus in which the high frequency poweramplifying apparatus is incorporated, it is possible to provide a radiocommunication apparatus for a multi-band communication system which issuperior in performance and which can reduce the power consumption.

What is claimed is:
 1. A high frequency power amplifying apparatuscomprising: a plurality of amplifying sections each having a pluralityof amplifying stages including a first amplifying stage and a secondamplifying stage subsequent thereto, in which said first amplifyingstage has a first terminal for receiving an input signal thereto and asecond terminal for sending out an output signal depending on the inputsignal received by the first terminal of the first amplifying stage;said second amplifying stage has a first terminal for receiving an inputsignal depending on said output signal from said second terminal of saidfirst amplifying stage and a second terminal for sending out an outputsignal depending on said input signal received by the first terminal ofthe second amplifying stage; a first control terminal for receiving apower control signal; and a control circuit connected to said firstcontrol terminal and to said plurality of amplifying sections forcontrolling, in response to said power control signal, said amplifyingstages, so that said second amplifying stage has a gain higher than thatof said first amplifying stage.
 2. A high frequency power amplifyingapparatus according to claim 1, further comprising: a second controlterminal for receiving a switching signal; and a selection circuitconnected to said second control terminal and to said control circuitfor selectively making one of said plurality of amplifying sections inresponse to said switching signal received by said second controlterminal.
 3. A high frequency power amplifying apparatus comprising anamplifying section having a plurality of amplifying stages including afirst amplifying stage and a second amplifying stage subsequent thereto,in which said first amplifying stage has a first terminal for receivingan input signal thereto and a second terminal for sending out an outputsignal depending on the input signal received by the first terminal ofthe first amplifying stage; said second amplifying stage has a firstterminal for receiving an input signal depending on said output signalfrom said second terminal of said first amplifying stage and a secondterminal for sending out an output signal depending on said input signalreceived by the first terminal of the second amplifying stage; a firstcontrol terminal for receiving a power control signal; and a controlcircuit connected to said first control terminal and to said pluralityof amplifying stages for controlling, in response to said power controlsignal, said amplifying stages so that said second amplifying stage hasa gain higher than that of said first amplifying stage.
 4. A highfrequency power amplifying apparatus comprising: a plurality ofamplifying sections each having a plurality of amplifying stagesincluding a first amplifying stage and a second amplifying stagesubsequent thereto, in which said first amplifying stage has a firstterminal for receiving an input signal thereto and a second terminal forsending out an output signal depending on the input signal received bythe first terminal of the first amplifying stage; said second amplifyingstage has a first terminal for receiving an input signal depending onsaid output signal from said second terminal of said first amplifyingstage and a second terminal for sending out an output signal dependingon said input signal received by the first terminal of the secondamplifying stage; a first control terminal for receiving a power controlsignal; and a control circuit connected to said first control terminaland to said plurality of amplifying sections for applying, in responseto said power control signal, bias voltages to said first terminals ofsaid first and second amplifying stages, so that a bias voltage at thefirst terminal of said second amplifying stage is higher than that atthe first terminal of said first amplifying stage.
 5. A high frequencypower amplifying apparatus comprising an amplifying section having aplurality of amplifying stages including a first amplifying stage and asecond amplifying stage subsequent thereto, in which said firstamplifying stage has a first terminal for receiving an input signalthereto and a second terminal for sending out an output signal dependingon the input signal received by the first terminal of the firstamplifying stage; said second amplifying stage has a first terminal forreceiving an input signal depending on said output signal from saidsecond terminal of said first amplifying stage and a second terminal forsending out an output signal depending on said input signal received bythe first terminal of the second amplifying stage; a first controlterminal for receiving a power control signal; and a control circuitconnected to said first control terminal and to said plurality ofamplifying stages for applying, in response to said power controlsignal, bias voltages to said first terminals of said first and secondamplifying stage, so that a bias voltage at the first terminal of saidsecond amplifying stage is higher than that at the first terminal ofsaid first amplifying stage.